1. Field of the Invention
The present invention relates to a short-stroke wall soot blower, for a furnace, which rotates and reciprocates its lance between the operative and inoperative positions of the lance. More specifically, the present invention relates to activating a wall soot blower in rotation and reciprocation by mechanical coupling to a single power source.
2. Description of the Prior Art
Combustion of fuels in a utility boiler produces huge amounts of particulate matter which accumulates on heated surfaces and reduces the heat transfer from the combustion to liquids to be vaporized. Coal firing is very productive of particulate matter, be it in the form of soot and/or slag. The lower the quality of coal, the more quickly is the accumulation of particulate matter on surfaces heated by the combustion. Removing structure must be frequently inserted into the furnace space to sheer away the accumulations which are the enemies of heat transfer.
Enter the soot blower. Essentially, the soot blower is a conduit, with a nozzle at its end, inserted into a hole in the wall of the furnace. Steam, or air is fed into the tube and ejected from its nozzle with great force. Correctly directed in the form of a spray, the fluid belching from this conduit can effectively shear particulate matter from large areas of the heated surfaces.
In the huge, multi-storied utility boiler, it is not uncommon to supply up to 300 soot blowers or more. Rows of these blowers are mounted at their furnace openings, the rows being on the order of vertical and horizontal 8' centers. Further, the lances of the blowers are reciprocated between their operative and inoperative positions to sequentially cut at the accumulations on the heating surfaces and maintain the efficiency of heat transfer from the combustion process to the vaporizable liquid behind the heating surfaces.
The environment in which the soot blower operates is inherently dirty. Coal dust in the atmosphere about a boiler is an unavoidable fact of the life of this tool. This dirt is an enemy to the mechanical system between the electric or air motive means and the soot blower with which the motive means rotates and reciprocates the soot blower lance.
In the short stroke wall blower, there is the problem of coring the vapor conduit, or lance, through its furnace opening which has been bridged by an accumulation of slag. It is necessary that this obstruction be cored through to bring the lance into its operative position. Therefore, a mechanism is necessary to actuate the lance and its cutting elements mounted thereon to position the nozzle end of the lance within the furnace. Once into the interior of the furnace, cleaning fluid is discharged in a pattern which will dislodge the accumulation of particulate matter from the internal wall of the furnace. Although other fluids could be employed, high pressure steam is the most available cleaning medium. The steam is conducted to each blower through a feed tube and the outer casing of the lance is rotated and reciprocated over a substantial length of the feed tube. Obviously, some form of seal between the outer surface of the feed tube and the rear of the lance casing is necessary to contain the cleaning medium and force it from a nozzle mounted on the forward end of the casing. Thus, in the environment about the utility boiler, which is hostile to mechanical motion and sealing, are the problems of dirt isolation to preserve efficient articulation of the parts of the blower which must move relative to each other.